Question: $4de + 7df - 7d + 2 = 2e - 9$ Solve for $d$.
Solution: Combine constant terms on the right. $4de + 7df - 7d + {2} = 2e - {9}$ $4de + 7df - 7d = 2e - {11}$ Notice that all the terms on the left-hand side of the equation have $d$ in them. $4{d}e + 7{d}f - 7{d} = 2e - 11$ Factor out the $d$ ${d} \cdot \left( 4e + 7f - 7 \right) = 2e - 11$ Isolate the $d$ $d \cdot \left( {4e + 7f - 7} \right) = 2e - 11$ $d = \dfrac{ 2e - 11 }{ {4e + 7f - 7} }$